Response with pembrolizumab in a patient with EGFR mutated non-small cell lung cancer harbouring insertion mutations in V834L and L858R

Introduction Lung cancer is the leading cause of cancer-related deaths with non-small cell lung cancer (NSCLC) being the most common of them. About a third of NSCLC cases have an epidermal growth factor (EGFR) mutation, which is usually susceptible to tyrosine kinase inhibitors (TKIs). In rare cases where patients progress through TKI therapy, the use of immune checkpoint inhibitors (ICIs) remains controversial. Case report We describe a case of a patient with significant history of smoking and EGFR mutated programmed death ligand-1 (PD-L1) positive NSCLC who was initially treated with TKI therapy. Management/Outcome While patient progressed on TKI therapy, he was able to achieve a durable response with a single PD-L1 agent, pembrolizumab. Contrary to the available evidence, the presented EGFR mutant NSCLC responded to PD-L1 pathway inhibition. Discussion From our observation Pembrolizumab could be promising in patients with rare EGFR mutations who do not respond to EGFR directed therapy. Our report provides supporting data for the use of immunotherapies in patients with EGFR mutated NSCLC.